The present invention relates to a method for managing files in a library including a plurality of recording media that record data as files. Further, the invention relates to a server device for library which is provided with a library including a plurality of recording media that record data as files, and distributes the data to a plurality of terminal units connected through a network.
In computers of late years, processing speed is higher, and spread of mass storage devices increases the amount of data that can be handled. As a device for storing mass data including character information, audio, moving pictures and the like, and regenerating or playing back the data according to requests of a plurality of terminal units, a server for library has received attention. Generally, file servers distribute data to a plurality of terminals through a network. Among such file servers, a server for library has a library including a plurality of recording media that are relatively low-priced and of large capacity, such as optical disks, as a main storage device, and has been expected in uses for handling mass data, such as multimedia.
A description is given of a conventional server for library that handles moving picture data.
FIG. 27 is a diagram illustrating a conventional network system having a library. Reference numeral 1 designates a library, and the library 1 keeps many disks, such as optical disks, as recording media that record data. Reference numerals 2 to 6 designate disks that record data, and the recorded data are treated as files. Reference numeral 11 designates a disk storage unit that stores the disks. Reference numerals 12 to 15 designate drives for inserting the disks and performing record and playback. Reference numeral 16 designates an arm for inserting/removing the disks into/from the disk storage unit 11 and the drives 12 to 15 and conveying the disks. Reference numeral 17 designates an arm control unit for controlling the operation of the arm 16. Reference numeral 18 designates a bus for transferring data of the disks that are inserted into the drives 12 to 15 and transferring control data to the arm control unit 17. Reference numeral 19 designates a server for library utilizing a personal computer or a work station. Reference numeral 20 designates a hard disk that records contents of the disks in the library 1, records of requests from terminal units, playback request frequency information on the basis of the request records and the like. This hard disk 20 is a storage device that can access the disks in the library 1 at high speed. Reference numeral 24 designates a network that is connected to the server 19, and numerals 25 to 28 designate terminal units that read out the files in the server 19 through the network 24. In this case, the data recorded on the disks are moving picture files which are rapidly increasing in recent years, and in order to perform continuous playback, the data should be transferred at a constant transfer rate or more.
A description is given of the operation when the server for library 19 with the construction described above plays back a file that is recorded on a disk in the library 1, according to a request from a terminal unit.
One of the terminal units 25 to 28 specifies a file name of a file to be played back and makes a playback request of the file to the server 19 Through the network 24. Referring to the contents of the disks in the library 1 that are recorded on the hard disk 20, the server 19 reads out information of the files recorded on the disks 2 to 6, and examines which of tho disks has the desired file. Then, when finding information of the desired file, the server 19 transfers control data to the arm control unit 17 of the library 1 through the bus 18. In the library 1, the arm control unit 17 moves the arm 16 according to the control data. The arm 16 removes tile disk including the desired file from the disk storage unit 11 to convey and insert the disk into one of the drives 12 to 15.
When readout of the desired file in the disk starts, tell server 19 adds a network address to the data to output the data with the network address to the network 24. The terminal unit. that has requested the file with the same network address receives this data to perform playback of the data.
In such a construction, when files in disks are read out and transferred to terminal units, disks in a library that can be removed from drives are generally lower in access speed than a hard disk or the like. In addition, in order to continuously playback specified moving picture data, it is required to transfer the data at a constant transfer rate or more. Therefore, in a case of media in which the access speed is low, such as the disks in the library, when a plurality of files in one disk are simultaneously read out, the transfer rate is not satisfactory for playback of moving picture data because of the slow readout. As a result, in playing back the moving picture data in terminal units, there occur the defects that, for example, the moving pictures impermanently stop. Consequently, it is usual to set the number of simultaneous readout files in one disk, which number is capable of transferring the moving pictures without producing the defects in the terminal units. Generally, the number of simultaneous readout files is set to 1. That is, concerning the disks in the library, a plurality of files in one disk cannot be simultaneously read out.
Meanwhile, concerning data that are recorded in a storage device in which the readout speed is high, such as a hard disk, it is possible to read out and transfer a plurality of files in the identical modium according to a plurality of playback requests, and perform continuous regeneration.
In a conventional server device, in order to accept requests from a plurality of terminal units as many as possible, a part of files that are retained in a library is copied to a hard disk. More specifically, the server device keeps records of the files that have received playback requests from the terminal units, in the hard disk, and frequency information about playback request frequency of the files in the library is created at regular intervals on the basis of the records of the playback requests. The files of high frequency in playback request are copied from the disks including tho files to the hard disk. Thereby, the plurality of files are read out of the hard disk in which the access speed is high to output moving pictures to the terminal units.
Further, for example, as disclosed by Japanese Published Patent Application No. Hei. 8-54991, one of disk media that has been read/written is left as it is inserted into a drive, and when data in the disk medium receive an access request, the data can be read/written immediately, thereby improving the access performance.
In the conventional server for library constructed as described above, the files of high frequency in playback request from the terminal units are successively copied from the disks to the hard disk. However, since the capacity of the hard disk is smaller than the capacity of the library, the hard disk is full of the files in a short time, failing to copy the files any more. In order to avoid this problem, among the files that have been copied to the hard disk, the files of low frequency in playback request are erased. As a result, however, only very few files of the files that have been retained in the library can be copied and retained in the hard disk, so that acceptance of the requests from the plurality of terminal units is restricted depending on the capacity of the hard disk.
Even when the operator of the server for library predicts that a file that is newly recorded in the library will receive many playback requests, or that a file will receive few playback requests in the future, there is no means of reflecting the prediction, and the operator only waits an increase or reduction in the playback request frequency. Therefore, acceptance of the requests from the plurality of terminal units is delayed, so That the server cannot be operated with good efficiency with the prediction by the operator made the best of.
Further, in determining whether the moving picture files in the disks are copied or not according to the frequency information of the file playback requests from the terminal units, the number of file playback requests in a prescribed time is usually used as the frequency information. Therefore, when a file has recently received suddenly increasing playback requests although the absolute number of the file playback requests in a prescribed time is not so large, the file is not copied until the requests of the file satisfactorily increase. Consequently, the moving pictures are not transferred simultaneously to the plurality of terminal units until that, thereby delaying acceptance of the requests.
Furthermore, if it is determined whether the files are copied or not according to only the playback request frequency, tie server copies a file that has been requested from the identical terminal unit many times, and does not copy a file that has often received requests from the plurality of terminal units at the identical time although the absolute number of the requests is not so large. As a result, the substance of the requests from the plurality of terminal units may be taken into consideration.
Furthermore, when the moving picture file in the disk is copied to the hard disk, the access speed of the hard disk is high and the access speed of the disk is lower than that of the hard disk. Therefore, the time required for copying the file to the hard disk depends on the access speed of the disk, resulting in long time for copying.
It is an object of the present invention to provide a method for managing files in a library and a server device for library, in which more requests from a plurality of terminal units can be accepted utilizing a library of larger capacity, regardless of limitation of the capacity of a storage device of high-speed access, such as a hard disk, in copying files in the library.
Another object of the present invention is to provide a method for managing files in a library and a server device for library, in which copies of files in a library can be created or erased according to instructions by the operator when an increase or reduction in requests of the files from terminal units is predicted, thereby operating the server more flexibly and more efficient.
Further object of the present invention is to provide a method for managing files in a library and a server device for library, in which files that have received increasing requests in time rear the present time can be copied with priority given, thereby accepting requests from a plurality of terminal units earlier.
Still further object of the present invention is to provide a method for managing files in a library and a server device for library, in which files that have often received simultaneous playback requests can be copied with priority given, thereby accepting requests from a plurality of terminal units more flexibly.
Still further object of the present invention is to provide a method for managing files in a library and a server device for library, in which files in a library can be copied to a hard disk in a shorter time by making the best of high-speed access of the hard disk.
Other objects and advantages of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific embodiment are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description.
According to a first aspect of the present invention, a method for managing files in a library with a manner to access files in a library operating with a plurality of preservation recording media or recording/playback devices storing data as files, while copying data more highly required to be reproduced to another storage device of high-speed access, the method comprising the steps of:
recording a playback request of said file when is required;
creating frequency information of playback request of each file according to said playback request; and
copying a file which is judged that it has very frequent playback requests compared to other files recorded in said preservation recording media according to said frequency information of playback request, at specified time intervals or when the number of said playback requests reaches a specified value.
According to a second aspect of the present invention, a method for managing files in a library of the claim 1 wherein: files in said preservation recording media are copied to another preservation recording medium according to instruction of the operator.
According to a third aspect of the present invention, a method for managing files in a library of the claim 1 wherein: said frequency information of regeneration request is changed according to instruction of the operator.
According to a fourth aspect of the present invention, a method for managing files in a library of the claim 1 wherein: said copying step is performed according to said frequency information of playback request in the case that a plurality of set of said specified time interval or said specified value of playback requests are used.
According to a fifth aspect of the present invention, a method for managing files in a library of the claim 1 wherein: when a file is required for another reproduction at the same time the file is already being reproduced according to the playback request, this tact is recorded as simultaneous playback request, the frequency information of said simultaneous playback request of the file is created according to said recorded simultaneous playback request; thereafter, according to said frequency information of playback request and said frequency information of simultaneous playback request, said copying step is performed.
According to a sixth aspect of the present invention, a method for managing files in a library of the claim 1 wherein: when a file recorded in a preservation recording medium is copied to another preservation recording medium in said library, a new name is given to said file and the relationship between the file name in said preservation recording medium and the file name of said another preservation recording medium is stored; and a file is selected when there is a regeneration request, referring to said relationship between said filenames.
According to a seventh aspect of the present invention, a method for managing files in a library of the claim 1 wherein: when copies and plays back files in said plurality of preservation recording media, priority of performance is determined.
According to an eighth aspect of the present invention, a method for managing files in a library of the claim 1 wherein: when a file in said library recorded in a preservation recording medium is copied to said storage device of high-speed access, if the same file as said file is already copied to another preservation recording medium, said files are in parallel read out from said preservation recording medium and said another preservation recording medium respectively and then copied to said storage device of high-speed access.
According to a ninth aspect of the present invention, a server device for library which has a library operating a plurality of preservation recording media storing data as files and transfer said data to a plurality of terminal apparatuses connected to said server via networks, the server device for library comprising:
storage device of high-speed access for reading out and writing data from and to said preservation recording media
playback request management unit for recording a playback request when said terminal apparatus requires said reproduction, and creating frequency information of said playback request from said terminal apparatus according to said storage of said playback request;
file management unit for copying a file which is judged that it has very frequent playback requests compared to other files recorded in said preservation recording media according to said frequency information of playback requests, at specified time intervals or when the number of said playback requests reaches a specified value; and
readout control unit for reading out files from said preservation recording media and said storage devices of high-speed access.
According to a tenth aspect of the present invention, a server device for library wherein: input means for receiving instruction of the operator is provided; and
said file management unit copies files stored in preservation recording media to another storage medium in said library according to instruction of the operator received by said input means.
According to an eleventh aspect of the present invention, a server device for library wherein: input means for receiving instruction of the operator is provided; and
said regeneration request management unit changes said frequency information of playback request according to instruction of the operator received by said input means.
According to a twelfth aspect of the present invention, a server device for library wherein: said file management unit performs said copying step according to said frequency information of playback request in the case that a plurality of set of said specified time interval or said specified value of playback requests are used.
According to a thirteenth aspect of the present invention, a server device for library wherein: in said playback request management unit, when a file is required for another playback at the same time the file is already being played back according to the playback request from a terminal apparatus, this fact is recorded as simultaneous playback request, the frequency information of said simultaneous request of the file is created according to said recorded simultaneous playback request; thereafter, according to said said frequency information of playback request and said frequency information of simultaneous playback request, said copying step is performed.
According to a fourteenth aspect of the present invention, a server device for library wherein: in said file management unit, when a file recorded in a preservation recording medium is copied to another preservation recording medium in said library, a new name is given to said file and the relationship between the file name in said preservation recording medium and the file name of said another preservation recording medium is stored; and a file is selected when there is a playback request, referring to said relationship between said filenames.
According to a fifteenth aspect of the present invention, a server device for library wherein: in said file management unit, when copies and played back files in said plurality of preservation recording media, priority of performance is determined.
According to a sixteenth aspect of the present invention, a server device for library wherein: in said file management unit, when a file in said library recorded in a preservation recording medium is copied to said storage device of high-speed access, if the same file as said file is already copied to another preservation recording medium, said files are in parallel read out from said preservation recording medium and said another preservation recording medium respectively and then copied to said storage device of high-speed access.